[EvanAnderson]

Apparently there's a 4th edition coming, but if you like the form-factor of a book-length text I'd throw a recommendation to "Database Design for Mere Mortals"[1]. I read the 1st edition from the late 90's, but I'd imagine it's still just as good. It approaches database modeling from a practical non-technical perspective, and I found it helped me learn data modeling in a software-agnostic manner, and later to influence how I talked to non-technical audiences about data modeling. I'm really glad to have found it early in my career.

I will echo what others have said. Data modeling is a force-multiplier type of skill. Combine it with a reasonable understanding of SQL and you can return a lot of value very quickly.

[1] https://www.amazon.com/Database-Design-Mere-Mortals-Hands/dp...

[ticmasta]

Not required, but knowing a little relational algebra helps queries make a lot more sense. A lot of the features like constraints and indices are very thin veneer over the underlying concepts.

At the other end of the spectrum, once you can write a few basic queries check out something like SQL Murder Mystery https://mystery.knightlab.com/

This one is super-fun and lets you practice some basic to low-intermediate skills.

[fizixer]

Fun fact: You can do relational algebra on plain text data (e.g., csv, as well as output of commands like ls, etc.) using only shell + piping + well-known shell tools.